We see from Fig REF  that capturing all the positional information encoded by Hb requires measuring the expression level with \(\sim 3\,{\rm bits}\)  of precision, consistent with our conclusions from the analysis of threshold models. We have done the same analysis for the other gap genes (Kr, Gt, and Kni), with the same conclusion.
How does this compare with the information capacity of real genetic regulatory elements? Estimates based both on direct measurements and on more detailed models indicate that this capacity is in the range of \(1-3\,{\rm bits}\)  [1]}, [2]}. This shows that it is possible for cells to extract all the available positional information using a handful of enhancers, but this requires that they operate close to the physical limits to information capacity. At the same time, it is clear from Fig REF  that there is a very big difference between a capacity of \(1\,{\rm bit}\)  and \(3\,{\rm bits}\) .
